help with timed night light

hi guys.

im a new member here and have just started on some very simple circuits.

at the moment i am trying to make a circuit that acts as a night light that turns on a set of LEDS for a set period of time (e.g. 3 minutes) when either a motion sensor is triggered or i move my hand through a directed beam of light.

i havent got to understanding programing microcontrollers yet so if there is a way that doesnt require any programming please could you advise me

thanks
Pape21

Do some reading on the 555 timer IC. Here is just one of many sites on it.

**broken link removed**

A micro controller would work, but isn't really needed. Spend an hour or so reading up on the 555, its very common and very versatile.

thanks for the advice.

from what i have managed to understand, i need to make a monostable oneshot 555 circuit and use a 2200uf capactor and a 100k resistor ( for the light to come on for 3 minutes then go off untill the circuit is triggered again)

could someone confirm this for me please

Nice try, unfortunately the leakage will probably be too high.

Use a 220:mu:F tantalum and a 1M, a CMOS 7555 is probably also a good idea.

pape21 said:

thanks for the advice.

from what i have managed to understand, i need to make a monostable oneshot 555 circuit and use a 2200uf capactor and a 100k resistor ( for the light to come on for 3 minutes then go off untill the circuit is triggered again)

could someone confirm this for me please

Click to expand...

I worked on a similar project where my circuit had to wait exactly 1 minute from turn-on time. at the end of 1 minute a motor was turned on. long story short, I used a big capacitor to get my big time constant--big mistake. try to make the cap smaller. in non-technical language, the 555 couldnt supply enough current fast enough to charge the big caps, or so i suspect... smaller caps, bigger resistor.

thanks for all your help guys.

i have finished my project now and made a box for it and i will post a picture of it when i get my camera charged